Catalyst comprising a zeolite y globally non-dealuminated and containing boron and/or silicon

ABSTRACT

A catalyst comprising 0.1-99.7% by weight of at least one alumina matrix; 0.1-80% by weight of at least one globally non dealuminated Y zeolite with a lattice parameter of more than 2.438 nm, a global SiO 2 /Al 2 O 3  mole ratio of less than 8, and a framework SiO 2 /Al 2 O 3  mole ratio of less than 21 and more than the global SiO 2 /Al 2 O 3  mole ratio; 0.1-30% by weight of at least one group VIII metal and/or 1-40% by weight of at least one group VIB metal (% oxide); 0.1-20% by weight of at least one promoter element selected from the group formed by boron and silicon (% oxide); 0-20% by weight of at least one group VIIA element; 0-20% by weight of phosphorous (% oxide); 0.1-20% by weight of at least one group VIIB element, useful for hydrocracking processes, especially at low pressures of 7.5 to 11 MPa.

[0001] The present invention relates to a catalyst for hydrocrackinghydrocarbon-containing feeds, said catalyst comprising at least onemetal selected from group VIB and group VIII (group 6 and groups 8, 9and 10 in the new notation for the periodic table: Handbook of Chemistryand Physics, 76^(th) edition, 1995-96), preferably molybdenum ortungsten, cobalt, nickel or iron, associated with a support comprisingan amorphous or low crystallinity oxide type alumina and a nondealuminated Y zeolite with a lattice parameter of more than 2.438 nm.The alumina matrix of the catalyst comprises boron and/or silicon andoptionally phosphorous, and optionally at least one element from groupVIIA (group 17, the halogens), in particular fluorine, and optionally atleast one group VIIB element.

[0002] The present invention also relates to processes for preparingsaid catalyst, and to its use for hydrocracking hydrocarbon-containingfeeds such as petroleum cuts, or cuts from coal containing sulphur andnitrogen in the form of organic compounds, such feeds possiblycontaining metals and/or oxygen.

[0003] Conventional hydrocracking of petroleum feeds is a very importantrefining process which produces lighter fractions such as gasoline, jetfuel and light gas oil from surplus heavy feeds, which lighter fractionsare needed by the refiner so that he can match production to demand. Theimportance of catalytic hydrocracking over catalytic cracking is that itcan provide very good quality middle distillates, jet fuels and gasoils.

[0004] All catalysts used for hydrocracking are bifunctional, combiningan acid function and a hydrogenating function. The acid function issupplied by large surface area supports (150 to 800 m²/g in general)with a superficial acidity, such as halogenated aluminas (in particularfluorinated or chlorinated), combinations of boron and aluminium oxides,amorphous silica-aluminas and zeolites. The hydrogenating function issupplied either by one or more metals from group VIII of the periodictable, such as iron, cobalt, nickel, ruthenium, rhodium, palladium,osmium, iridium or platinum, or by a combination of at least one metalfrom group VIB of the periodic table such as chromium, molybdenum ortungsten, and at least one group VIII metal, preferably non noble.

[0005] The equilibrium between the two, acid and hydrogenating,functions is the fundamental parameter which governs the activity andselectivity of the catalyst. A weak acid function and a stronghydrogenating function produces low activity catalysts which generallyoperate at a high temperature (390° C. or above), and at a low supplyspace velocity (HSV, expressed as the volume of feed to be treated perunit volume of catalyst per hour, and is generally 2 or less), but havevery good selectivity for middle distillates. In contrast, a strong acidfunction and a weak hydrogenating function produces very activecatalysts but selectivities for middle distillates are poor. Further, aweak acid function is less sensitive to deactivation, in particular bynitrogen-containing compounds, than a strong acid function. The problemis thus the proper selection of each of the functions to adjust theactivity/selectivity balance of the catalyst.

[0006] Weakly acid supports are generally constituted by amorphous orlow crystallinity oxides. Weakly acidic supports include amorphoussilica-aluminas. Certain catalysts on the hydrocracking market areconstituted by silica-alumina combined with a combination of sulphidesof groups VIB and VIII metals. Such catalysts enable feeds containinglarge quantities of heteroatomic poisons, sulphur and nitrogen, to betreated. The selectivity of such catalysts for middle distillates isvery good. The disadvantage of such catalytic systems based on anamorphous support is their low activity.

[0007] Supports with a high acidity generally contain a dealuminatedzeolite, for example a dealuminated Y type zeolite or USY (Ultra StableY zeolite), combined with a binder, for example alumina. Certaincatalysts on the hydrocracking market are constituted by a dealuminatedY zeolite and an alumina combined either with a group VIII metal or witha combination of sulphides of group VIB and VIII metals. Such catalystsare preferably used to treat feeds containing less than 0.01% by weightof heteroatomic poisons, sulphur and nitrogen. Such systems are veryactive and the products formed are of high quality. The disadvantage ofsuch catalytic systems based on a zeolitic support is that theirselectivity for middle distillates is a little poorer than catalystsbased on an amorphous support, and a high sensitivity to nitrogencontent. Such catalysts can only tolerate low amounts of nitrogen in thefeed, in general less than 100 ppm by weight.

[0008] The Applicant has discovered that to obtain a hydrocrackingcatalyst with good activity and good stability for feeds with highnitrogen contents, it is advantageous to combine an alumina type acidicamorphous oxide matrix doped with at least one element selected fromboron and silicon, and optionally phosphorous and optionally at leastone group VIIA element, in particular fluorine, with a highly acidicglobally dealuminated Y zeolite.

[0009] The term “globally non dealuminated zeolite” means a Y zeolitewith a faujasite structure (“Zeolite Molecular Sieves: Structure,Chemistry and Uses”, D. W. BRECK, J. Wiley & Sons, 1973). The latticeparameter of this zeolite may have been reduced by extracting aluminiumfrom the structure or framework during its preparation but the globalSiO₂/Al₂O₃ ratio is not changed since the aluminium atoms have not beenchemically extracted. The zeolite crystals thus contain aluminiumextracted from the framework in the form of extra-framework aluminium.Such a globally non dealuminated zeolite thus has a silicon andaluminium composition, expressed as the global SiO₂/Al₂O₃ ratio,equivalent to the non dealuminated starting Y zeolite. This globally nondealuminated Y zeolite can be in its hydrogen form, i.e., at leastpartially exchanged with metal cations, for example using cations ofalkaline-earth metals and/or cations of rare earth metals with atomicnumber 57 to 71 inclusive.

[0010] The catalyst of the present invention generally comprises atleast one metal selected from the following groups in the followingamounts, as a percentage by weight with respect to the total catalystmass:

[0011] 0.1% to 30% of at least one group VIII metal and/or 1-40% of atleast one group VIB metal (% oxide);

[0012] 1% to 99.7%, preferably 10% to 98%, more preferably 15% to 95%,of at least one amorphous or low crystallinity alumina matrix;

[0013] 0.1% to 80%, or 0.1% to 60%, preferably 0.1% to 50%, of at leastone globally non dealuminated Y zeolite with a lattice parameter of morethan 2.438 nm, a global SiO₂/Al₂O₃ mole ratio of less than 8, and aframework SiO₂/Al₂O₃ mole ratio, calculated using theFichtner-Schmittler correlation (Cryst. Res. Tech. 1984, 19, K1) of lessthan 21 and above the global SiO₂/Al₂O₃ ratio;

[0014] 0.1% to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%,of at least one promoter element selected from the group formed by boronand silicon (% oxide);

[0015] and optionally:

[0016] 0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10%, ofphosphorous (% oxide);

[0017] 0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10% byweight, of at least one element selected from group VIIA, preferablyfluorine;

[0018] 0 to 20%, preferably 0.1% to 15%, more preferably 0.1% to 10% byweight, of at least one element selected from group VIIB, preferablymanganese or rhenium.

[0019] The catalysts obtained in the present invention are formed intograins of different shapes and dimensions. They are generally used inthe form of cylindrical or polylobed extrudates such as bilobes,trilobes, or polylobes with a straight or twisted shape, but they canalso be produced and used in the form of compressed powder, tablets,rings, beads or wheels. The specific surface area is measured bynitrogen adsorption using the BET method (Brunauer, Emmett, Teller, J.Am. Chem. Soc., vol. 60, 309-316 (1938)) and is more than 140 m²/g, thepore volume measured using a mercury porisimeter is in the range 0.2 to1.5 cm^(3/)g and the pore size distribution may be unimodal, bimodal orpolymodal. Preferably, the distribution of the catalysts of the presentinvention is unimodal.

[0020] The activity of said catalyst for hydrocracking vacuum gas oiltype cuts is higher than that of known catalytic formulae of the priorart. Without wishing to be bound by any particular theory, it appearsthat the particularly high activity of the catalysts of the presentinvention is due to a reinforcement in the acidity of the catalyst bythe presence of an alumina matrix acidified by the addition of boronand/or silicon, which also improves the hydrodenitrogenation propertiesof the active phase comprising at least one group VIB metal andoptionally at least one group VIII metal, and by the presence of thehighly acidic Y zeolite a large portion of the acidity of which will beneutralised by nitrogen-containing compounds, but the acidic sites whichremain under the operating conditions will result in sufficienthydrocracking activity for the catalyst.

[0021] The catalyst of the present invention can be prepared using anyof the methods which are known to the skilled person.

[0022] Advantageously, it is obtained by mixing a source of alumina,optionally doped with boron and/or silicon, and a source of the startingY zeolite, the mixture then being formed. All or a portion of the groupVIII and/or VIB elements, the group VIIA element and the phosphorous isintroduced during mixing, or all of it can be introduced after forming(preferred). Forming is followed by calcining at a temperature of 250°C. to 600° C. One preferred forming method consists of mixing thestarting Y zeolite in a moist alumina gel for a few tens of minutes,then passing the paste obtained through a die to form extrudates with adiameter which is preferably in the range 0.4 to 4 mm.

[0023] The alumina source is normally selected from the group formed byalumina gels and alumina powders obtained by calcining aluminiumhydroxides and oxyhydroxides. Preferably, matrices containing aluminaare used, in any of the forms known to the skilled person, for examplegamma alumina.

[0024] The preferred Y zeolite source is a Y zeolite powdercharacterized by different specifications: a lattice parameter of morethan 2.451 nm; a global SiO₂/AI₂O₃ mole ratio of less than 8, aframework SiO₂/Al₂O₃ mole ratio, calculated using theFichtner-Schmittler correlation (Cryst. Res. Tech. 1984, 19, K1) of lessthan 11; a sodium content of less than 0.2% by weight determined for thezeolite calcined at 1100° C.; and a specific surface area, determinedusing the BET method, of more than about 400 m²/g, preferably more than600 m²/g.

[0025] The catalyst also comprises a hydrogenating function. Thehydrogenating function is provided by at least one metal or compound ofa metal from group VIB such as molybdenum or tungsten. A combination ofat least one metal or compound of a metal from group VIB of the periodictable (in particular molybdenum or tungsten) and at least one metal orcompound of a metal from group VIII of the periodic table, preferablynon noble (in particular cobalt or nickel) can be used.

[0026] The hydrogenating function as defined above can be introducedinto the catalyst at various stages of the preparation and in variousmanners. It can be introduced only partially (in the case, for exampleof combinations of oxides of groups VIB and VIII metals) or completelyon mixing the alumina source, the remaining hydrogenating element(s)then being introduced after mixing, more generally after calcining.Preferably, the group VIII metal is introduced simultaneously with orafter the group VIB metal, regardless of its mode of introduction. Itcan be introduced by one or more ion exchange operations carried out onthe calcined support constituted by the zeolite dispersed in the aluminamatrix, using solutions containing precursor salts of the selectedmetals when these are from group VIII. It can be introduced by one ormore steps for impregnating the formed and calcined support using asolution of precursors of group VIII metal oxides (in particular cobaltor nickel) when the precursors of the group VIB metal oxides (inparticular molybdenum or tungsten) have already been introduced onmixing the support. Finally, it can also be introduced by one or moresteps for impregnating the calcined support constituted by the zeoliteand alumina matrix, optionally doped with B, Si, P and/or F, usingsolutions containing precursors of oxides of group VIB and/or group VIIImetals, the precursors of the oxides of the group VIII metal preferablybeing introduced after those of group VIB or at the same time as thelatter.

[0027] When the elements are introduced in a plurality of steps forimpregnating the corresponding precursor salts, an intermediatecalcining step must be carried out on the catalyst at a temperature inthe range 250° C. to 600° C.

[0028] The sources of the group VIB element which can be used are wellknown to the skilled person. As an example, preferred sources ofmolybdenum and of tungsten are ammonium salts and oxides such asammonium molybdate, ammonium heptamolybdate and ammonium tungstate.

[0029] The sources of the group VIII element which can be used are wellknown to the skilled person. As an example, nitrates, sulphates andhalides can be used.

[0030] The sources of the group VIIB elements which can be used are wellknown to the skilled person. Preferably, ammonium salts, nitrates andchlorides are used.

[0031] The phosphorous can be introduced into the catalyst at variousstages in the preparation and in a variety of manners. One preferredmethod consists of preparing an aqueous solution of at least one groupVIB element and optionally at least one group VIII element and aphosphorous compound and carrying out dry impregnation, in which thepore volume of the precursor is filled with the solution containing thegroup VIB metal, the optional group VIII metal, phosphorous and theoptional group VIIA element.

[0032] Molybdenum and/or tungsten impregnation can be facilitated byadding phosphoric acid to the solutions, which enables phosphorous to beintroduced as well to promote the catalytic activity. Other phosphorouscompounds can be used, as is well known to the skilled person.

[0033] The phosphorous and the element selected from group VIIA halideions can be introduced by one or more impregnation operations using anexcess of solution, carried out on the calcined precursor.

[0034] The preferred phosphorous source is orthophosphoric acid H₃PO₄,but its salts and esters such as ammonium phosphates are also suitable.Phosphomolybdic acid and its salts, phosphotungstic acid and its saltscan advantageously be used. Phosphorous can, for example, be introducedin the form of a mixture of phosphoric acid and a basic organic compoundcontaining nitrogen, such as ammonia, primary and secondary amines,cyclic amines, pyridine group compounds, quinolines, and pyrrole groupcompounds.

[0035] Introducing boron requires an aqueous solution containing boron(B) to be deposited. One preferred method consists of preparing anaqueous solution of at least one boron salt such as ammonium biborate orammonium pentaborate in an alkaline medium and in the presence of waterand carrying out “dry” impregnation, in which the pore volume of theprecursor is filled with the solution containing the B. This method fordepositing B is better than the conventional method employing analcoholic solution of boric acid.

[0036] The B and the optional element selected from group VIIA, thehalogens, preferably fluorine (F), can be introduced into the catalystat various stages of the preparation and in various manners.

[0037] The phosphorous (P), B and the element selected from halide ionsof group VIIA can be separately introduced into the calcined precursorusing one or more impregnation operations with an excess of solution.

[0038] Thus, for example, in the preferred case where, for example, theprecursor is a catalyst of the nickel-molybdenum-phosphorous supportedon alumina-Y zeolite type, it is possible to impregnate this precursorwith an aqueous solution of biborate, to dry, for example at 80° C.,then to impregnate with a solution of ammonium fluoride, to dry, forexample at 80° C., and to calcine, for example and preferably in air ina traversed bed, for example at 500° C. for 4 hours.

[0039] Introducing silicon requires an aqueous solution containingsilicon to be deposited. One preferred method of the invention consistsof preparing an aqueous solution containing a silicone type silicon (Si)compound in the form of an emulsion and to carry out “dry” impregnation,in which the pore volume of the precursor is filled with the solutioncontaining the Si. This method for depositing Si is better than theconventional method employing an alcoholic solution of ethylorthosilicate in alcohol.

[0040] A variety of silicon sources can be used. Examples are ethylorthosilicate Si(OEt)₄, silicones, siloxanes, polysiloxanes, andhalogenated silicates such as ammonium fluorosilicate (NH₄)₂SiF₆ orsodium fluorosilicate Na₂SiF₆. Silicomolybdic acid and its salts, andsilicotungstic acid and its salts can also advantageously be used.Silicon can be added, for example, by impregnating ethyl silicate insolution in a water/alcohol mixture. Silicon can be added, for example,by impregnation using an emulsion of a silicone in water.

[0041] Sources of group VIIA elements which can be used are well knownto the skilled person. As an example, fluoride anions can be introducedin the form of hydrofluoric acid or its salts. Such salts are formedwith alkali metals, ammonium or an organic compound. In the latter case,the salt is advantageously formed in the reaction mixture by reactingthe organic compound with hydrofluoric acid. It is also possible to usehydrolysable compounds which can liberate fluoride anions in water, suchas ammonium fluorosilicate (NH₄)₂SiF₆, silicon tetrafluoride SiF4 orsodium fluorosilicate Na₂SiF₆. Fluorine can be introduced, for example,by impregnating an aqueous hydrofluoride or ammonium fluoride solution.

[0042] The catalysts obtained are used for hydrocracking, in particularof vacuum distillate, deasphalted residues or hydrotreated type heavyhydrocarbon-containing feeds. The heavy feeds are preferably constitutedby at least 80% by volume of compounds with boiling points of at least350° C., preferably in the range 350° C. to 580° C. They generallycontain heteroatoms such as sulphur and nitrogen. The nitrogen contentis usually in the range 1 to 5000 ppm by weight and the sulphur contentis in the range 0.01% to 5% by weight.

[0043] The hydrocracking conditions such as temperature, pressure,hydrogen recycle ratio, and hourly space velocity, can vary widelydepending on the nature of the feed, the quality of the desired productsand the facilities available to the refiner. The temperature isgenerally more than 200° C. and usually in the range 250° C. to 480° C.The pressure is more than 0.1 MPa and usually more than 1 MPa. Thehydrogen recycle ratio is a minimum of 50 and usually in the range 80 to5000 normal liters of hydrogen per liter of feed. The hourly spacevelocity is generally in the range 0.1 to 20 volumes of feed per volumeof catalyst per hour.

[0044] The catalysts of the present invention preferably undergosulphurisation to transform at least part of the metallic species to thesulphide before bringing them into contact with the feed to be treated.This activation treatment by sulphurisation is well known to the skilledperson and can be carried out using any method already described in theliterature.

[0045] One conventional sulphurisation method which is well known to theskilled person consists of heating in the presence of hydrogen sulphideto a temperature in the range 150° C. to 800° C., preferably in therange 250° C. to 600° C., generally in a traversed bed reaction zone.

[0046] Finally, the composition of the catalyst renders it easy toregenerate.

[0047] The catalyst can be used under variable hydrocracking conditionswith pressures of at least 2 MPa, a reaction temperature of at least230° C., an H₂/feed ratio of at least 100 Nl H₂/l of feed and an hourlyspace velocity of 0.1-10 h⁻¹.

[0048] The initial boiling point of the hydrocarbon-containing feedstreated is at least 150° C., preferably at least 350° C., moreadvantageously a cut boiling between 350-580° C.

[0049] The catalyst of the present invention can be used forhydrocracking a variety of hydrocarbon-containing cuts, for examplevacuum distillate type cuts containing large amounts of sulphur andnitrogen. In a first partial hydrocracking implementation, the degree ofconversion is below 55%. The catalyst of the invention is thus used at atemperature which is generally 230° C. or more, or 300° C., generally atmost 480° C., and usually in the range 350° C. to 450° C. The pressureis generally more than 2 MPa and 12 MPa or less. A moderate pressurerange is of particular interest, namely 7.5-11 MPa, preferably 7.5-10MPa or 8-11 MPa, advantageously 8.5-10 MPa. The quantity of hydrogen isa minimum of 100 normal liters of hydrogen per liter of feed and usuallyin the range 200 to 3000 normal liters of hydrogen per liter of feed.The hourly space velocity is generally in the range 0.1 to 10 h⁻¹. Underthese conditions, the catalysts of the present invention have betteractivities for conversion, hydrodesulphuration and hydrodenitrogenationthan commercially available catalysts.

[0050] In this implementation, the catalyst of the present invention canbe used for partial hydrocracking, advantageously under moderatehydrogen pressure conditions, of cuts such as vacuum distillatescontaining high sulphur and nitrogen contents which have already beenhydrotreated. In this hydrocracking mode, the degree of conversion isbelow 55%. In this case, the petroleum cut is converted in two steps,the catalysts of the invention being used in the second step. Thecatalyst used in the first step has a hydrotreatment function andcomprises a matrix, preferably alumina-based, preferably containing nozeolite, and at least one metal with a hydrogenating function. Saidmatrix can also be constituted by, or comprise, silica, silica-alumina,boron oxide, magnesia, zirconia, titanium oxide or a combination ofthese oxides. The hydrotreatment function is ensured by at least onemetal or compound of a metal from group VIII, such as nickel or cobalt.A combination of at least one metal or compound of a metal from groupVIB (in particular molybdenum or tungsten) and at least one metal orcompound of a metal from group VIII (in particular cobalt or nickel) canbe used. The total concentration of groups VIB and VIII metal oxides ispreferably in the range 5% to 40% by weight, preferably in the range 7%to 30% by weight, and the weight ratio, expressed as the metal oxide ofthe group VIB metal (or metals) to that of the group VIII metal (ormetals), is in the range 1.25 to 20, preferably in the range 2 to 10.Further, this catalyst can contain phosphorous. The phosphorous content,expressed as the concentration of phosphorous pentoxide P₂O₅, isgenerally at most 15%, preferably in the range 0.1% to 15% by weight,and more preferably in the range 0.15% to 10% by weight. It can alsocontain boron in a ratio B/P=1.05-2 (atomic), the sum of the B and Pcontents, expressed as the oxides, being in the range 5% to 15% byweight.

[0051] The first step is generally carried out at a temperature of350-460° C., preferably 360-450° C.; at a total pressure of 2 to 12 MPa,preferably 7.5-11 MPa, 7.5-10 MPa or 8-11 MPa or 8.5-10 MPa; and thehourly space velocity is 0.1-5 h⁻¹, preferably 0.2-2 h⁻¹, with aquantity of hydrogen at least 100 Nl/Nl of feed, preferably 260-3000Nl/Nl of feed.

[0052] In the conversion step using the catalyst of the invention (orsecond step), the temperatures are generally 230° C. or more and usuallyin the range 300° C. to 430° C. The pressure is generally in the range 2to 12 MPa, preferably 7.5-11 MPa or 7.5-10 MPa or 8-11 MPa or 8.5-10MPa. The quantity of hydrogen is a minimum of 100 l/l of feed andusually in the range 200 to 3000 liters of hydrogen per liter of feed.The hourly space velocity is generally in the range 0.15 to 10 h⁻¹.

[0053] Under these conditions, the activities of the catalysts of thepresent invention are better for conversion, hydrodesulphuration, andhydrodenitrogenation and the selectivity for middle distillates isbetter than that of commercially available catalysts. The service lifeof the catalysts is also improved in the moderate pressure range.

[0054] In a second implementation, the catalyst of the present inventioncan be used for hydrocracking under high hydrogen pressure conditions ofat least 8.5 MPa, preferably at least 9 MPa or at least 10 MPa. Thetreated cuts are, for example, vacuum distillates containing highsulphur and nitrogen contents which have already been hydrotreated. Inthis hydrocracking mode, the degree of conversion is more than 55%. Inthis case, the petroleum cut conversion process is carried out in twosteps, the catalyst of the invention being used in the second step.

[0055] The catalyst for the first step has a hydrotreatment function andcomprises a matrix, preferably alumina-based, preferably containing nozeolite, and at least one metal with a hydrogenating function. Saidmatrix can also be constituted by, or comprise, a silica,silica-alumina, boron oxide, magnesia, zirconia, titanium oxide or acombination of these oxides. The hydro-dehydrogenating function isensured by at least one group VIII metal or compound of a metal such asnickel or cobalt. A combination of at least one metal or compound of ametal from group VIB (in particular molybdenum or tungsten) and at leastone metal or compound of a metal from group VIII (in particular cobaltor nickel) can be used. The total concentration of group VIB and VIIImetal oxides is in the range 5% to 40% by weight, preferably in therange 7% to 30% by weight, and the weight ratio, expressed as the metaloxide of the group VIB metal (or metals) to that of the group VIII metal(or metals) is preferably in the range 1.25 to 20, more preferably inthe range 2 to 10. Further, this catalyst can contain phosphorous. Thephosphorous content, expressed as the concentration of phosphorouspentoxide P₂O₅, is at most 15%, preferably in the range 0.1% to 15% byweight, and more preferably in the range 0.15% to 10% by weight. It canalso contain boron in a ratio B/P=1.02-2 (atomic), the sum of the B andP contents, expressed as the oxides, preferably being in the range 5% to15% by weight.

[0056] The first step is generally carried out at a temperature of350-460° C., preferably 360-450° C.; the pressure is more than 8.5 MPa,preferably more than 10 MPa; the hourly space velocity is 0.1-5 h⁻¹,preferably 0.2-2 h⁻¹; and the quantity of hydrogen is at least 100 Nl/Nlof feed, preferably 260-3000 Nl/Nl of feed.

[0057] For the conversion step using the catalyst of the invention (orsecond step), the temperatures are generally 230° C. or more, usually inthe range 300° C. to 430° C. The pressure is generally more than 8.5MPa, preferably more than 10 MPa. The quantity of hydrogen is a minimumof 100 l/l of feed, usually in the range 200 to 3000 liters of hydrogenper liter of feed. The hourly space velocity is generally in the range0.15 to 10 h⁻¹.

[0058] Under these conditions, the activities of the catalysts of thepresent invention are better for conversion and the selectivity formiddle distillates is better than that for commercially availablecatalysts, even though the zeolite contents are considerably lower thanthose of commercially available catalysts.

[0059] The following examples illustrate the present invention withoutin any way limiting its scope.

EXAMPLE 1 Preparation of a support containing a non dealuminated Yzeolite

[0060] Large quantities of a hydrocracking catalyst support containing aglobally non dealuminated Y zeolite were produced so as to enabledifferent catalysts based on the same support to be prepared. To thisend, 19.7% by weight of a non dealuminated Y zeolite with a latticeparameter of 2.453 nm, a global SiO₂/Al₂O₃ ratio of 6.6 and a frameworkSiO₂/Al₂O₃ ratio of 8.6 was used, which was mixed with 80.3% by weightof a matrix composed of ultrafine tabular boehmite or alumina gel soldby Condéa Chemie GmbH under the trade name SB3. This powder mixture wasthen mixed with an aqueous solution containing 66% nitric acid (7% byweight of acid per gram of dry gel) then mixed for 15 minutes. Aftermixing, the paste obtained was passed through a die with cylindricalorifices with a diameter of 1.4 mm. The extrudates were dried overnightat 120° C. then calcined at 550° C. for 2 hours in moist air containing7.5% by volume of water. Cylindrical extrudates 1.2 mm in diameter wereobtained with a specific surface area of 351 m²/g, a pore volume of 0.58cm³/g and a unimodal pore size distribution centred on 10 nm. An X raydiffraction analysis of the matrix revealed that it was composed of lowcrystallinity cubic gamma alumina and Y zeolite with a lattice parameterof 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.7 with a frameworkSiO₂/Al₂O₃ ratio of 13.9.

EXAMPLE 2 Preparation of hydrocracking catalysts containing a nondealuminated Y zeolite

[0061] Extrudates of the support containing a non dealuminated Y zeolitewith a lattice parameter of 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.7and a framework SiO₂/Al₂O₃ ratio of 13.9 prepared in Example 1 were dryimpregnated with an aqueous solution of a mixture of ammoniumheptamolybdate and nickel nitrate, dried overnight at 120° C. in air andfinally calcined at 550° C. in air. The oxide weight contents ofcatalyst CZ3 obtained are shown in Table 1. The final CZ3 catalystcontained 16.6% by weight of Y zeolite. X ray diffraction analysis ofthe matrix revealed that it was composed of low crystallinity cubicgamma alumina and Y zeolite with a lattice parameter of 2.444 nm, aglobal SiO₂/Al₂O₃ ratio of 6.6 and a framework SiO₂/Al₂O₃ ratio of 14.2.

[0062] Catalyst CZ3 was then impregnated with an aqueous solutioncomprising ammonium biborate. After ageing at room temperature in anatmosphere saturated with water, the impregnated extrudates were driedovernight at 120° C. then calcined at 550° C. for 2 hours in dry air.Catalyst CZ3B was obtained: NiMo/alumina-Y doped with boron. In the sameway, catalyst CZ3Si was prepared by impregnating catalyst CZ3 with aRhodorsil EP1 (Rhone-Poulenc) silicone emulsion. The impregnatedextrudates were dried overnight at 120° C. then calcined at 550° C. for2 hours in dry air. Finally, catalyst CZ3BSi was prepared byimpregnating catalyst CZ3 with an aqueous solution comprising ammoniumbiborate and Rhodorsil EP1 (Rhone-Poulenc) silicone emulsion. Theimpregnated extrudates were dried overnight at 120° C. then calcined at550° C. for 2 hours in dry air.

[0063] Extrudates of the support containing the Y zeolite of Example 1were also dry impregnated with an aqueous solution of a mixture ofammonium heptamolybdate, nickel nitrate and orthophosphoric acid, driedovernight at 120° C. in air and finally calcined at 550° C. in air. Theoxide weight contents of catalyst CZ3P obtained are shown in Table 1.The final CZ3P catalyst contained 15.7% by weight of Y zeolite. X raydiffraction analysis of the matrix revealed that it was composed of lowcrystallinity cubic gamma alumina and Y zeolite with a lattice parameterof 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.7 and a framework SiO₂/Al₂O₃ratio of 14.7.

[0064] Catalyst CZ3P was then impregnated with an aqueous solutioncomprising ammonium biborate. After ageing at room temperature in anatmosphere saturated with water, the impregnated extrudates were driedovernight at 120° C. then calcined at 550° C. for 2 hours in dry air.Catalyst CZ3BP was obtained: NiMoP/alumina-Y doped with boron.

[0065] A catalyst CZ3PSi was prepared using the same procedure as forcatalyst CZ3PB, replacing the boron precursor in the impregnationsolution with Rhodorsil EP1 (Rhone-Poulenc) silicone emulsion.

[0066] Finally, catalyst CZ3PBSi was prepared by impregnating catalystCZ3P with an aqueous solution comprising ammonium biborate and RhodorsilEP1 (Rhone-Poulenc) silicone emulsion. The other steps of the procedurewere the same as those indicated above. The characteristics of catalystsCZ3 are summarised in Table 1. TABLE 1 Characteristics of CZ3 catalystsCZ3 CZ3 CZ3 CZ3 CZ3 CZ3 CZ3 Catalyst CZ3 P B Si BSi PB PSi PBSi MoO₃ (wt%) 13.1 12.5 12.8 12.8 12.5 12.3 12.3 12.1 NiO (wt %) 2.84 2.7 2.8 2.82.7 2.7 2.7 2.6 P₂O₅ (wt %) 0 5.2 0 0 0 5.1 5.1 5.0 B₂O₃ (wt %) 0 0 2.450 2.4 2.3 0 2.3 SiO₂ (wt %) 0 0 0 2.2 2.2 0 2.3 2.2 Al₂O₃ (wt %) 67.563.8 65.8 66.0 64.4 62.3 62.3 60.9 Y (wt %) 16.6 15.7 16.1 16.2 15.815.3 15.3 14.9

EXAMPLE 3 Preparation of a support containing a small amount of nondealuminated Y zeolite

[0067] Large quantities of a hydrocracking catalyst support containing asmall amount of a globally non dealuminated Y zeolite were produced soas to enable different catalysts based on the same support to beprepared. To this end, 8.6% by weight of a non dealuminated Y zeolitewith a lattice parameter of 2.453 nm, a global SiO₂/Al₂O₃ ratio of 6.6and a framework SiO₂/Al₂O₃ ratio of 8.6 was used, which was mixed with91.4% by weight of a matrix composed of ultrafine tabular boehmite oralumina gel sold by Condéa Chemie GmbH under the trade name SB3. Thispowder mixture was then mixed with an aqueous solution containing 66%nitric acid (7% by weight of acid per gram of dry gel) then mixed for 15minutes. After mixing, the paste obtained was passed through a die withcylindrical orifices with a diameter of 1.4 mm. The extrudates weredried overnight at 120° C. then calcined at 550° C. for 2 hours in moistair containing 7.5% by volume of water. Cylindrical extrudates 1.2 mm indiameter were obtained with a specific surface area of 259 m²/g, and apore volume of 0.57 cm³/g and a unimodal pore size distribution centredon 10 nm. An X ray diffraction analysis of the matrix revealed that itwas composed of low crystallinity cubic gamma alumina and Y zeolite witha lattice parameter of 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.7 with aframework SiO₂/Al₂O₃ ratio of 14.1.

EXAMPLE 4 Preparation of catalysts containing a small amount of nondealuminated Y zeolite

[0068] Extrudates of the support containing a small amount of nondealuminated Y zeolite with a lattice parameter of 2.444 nm, a globalSiO₂/Al₂O₃ ratio of 6.7 and a framework SiO₂/Al₂O₃ ratio of 14.1prepared in Example 3 were dry impregnated with an aqueous solution of amixture of ammonium heptamolybdate and nickel nitrate, dried overnightat 120° C. in air and finally calcined at 550° C. in air. The oxideweight contents of catalyst CZ5 obtained are shown in Table 2. The finalCZ5 catalyst contained 7.1% by weight of Y zeolite with a latticeparameter of 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.8 and a frameworkSiO₂/Al₂O₃ ratio of 14.9.

[0069] Catalyst CZ5 was then impregnated with an aqueous solutioncomprising ammonium biborate. After ageing at room temperature in anatmosphere saturated with water, the impregnated extrudates were driedovernight at 120° C. then calcined at 550° C. for 2 hours in dry air.Catalyst CZ5B was obtained. In the same way, catalyst CZ5Si was preparedby impregnating catalyst CZ5 with a Rhodorsil EP1 (Rhone-Poulenc)silicone emulsion. The impregnated extrudates were dried overnight at120° C. then calcined at 550° C. for 2 hours in dry air. Finally,catalyst CZ5BSi was prepared by impregnating catalyst CZ5 with anaqueous solution comprising ammonium biborate and Rhodorsil EP1(Rhone-Poulenc) silicone emulsion. The impregnated extrudates were driedovernight at 120° C. then calcined at 550° C. for 2 hours in dry air.

[0070] Extrudates of the support containing the Y zeolite of Example 3were also dry impregnated with an aqueous solution of a mixture ofammonium heptamolybdate, nickel nitrate and orthophosphoric acid, driedovernight at 120° C. in air and finally calcined at 550° C. in air. Theoxide weight contents of catalyst CZ5P obtained are shown in Table 2.

[0071] Catalyst CZ5P was then impregnated with an aqueous solutioncomprising ammonium biborate. After ageing at room temperature in anatmosphere saturated with water, the impregnated extrudates were driedovernight at 120° C. then calcined at 550° C. for 2 hours in dry air.Catalyst CZ5BP was obtained: NiMoP/alumina-Y doped with boron.

[0072] A catalyst CZ5PSi was prepared using the same procedure as forcatalyst CZ5PB, replacing the boron precursor in the impregnationsolution with Rhodorsil EP1 (Rhone-Poulenc) silicone emulsion.

[0073] Finally, catalyst CZ5PBSi was prepared by impregnating catalystCZ5P with an aqueous solution comprising ammonium biborate and RhodorsilEP1 (Rhone-Poulenc) silicone emulsion. The other steps of the procedurewas the same as those indicated above. Fluorine was then added to thiscatalyst by impregnating with a dilute hydrofluoric acid solution so asto deposit about 1% by weight of fluorine. After drying overnight at120° C. and calcining at 550° C. for 2 hours in dry air, catalystCZ5PBSiF was obtained. The characteristics of catalysts CZ5 aresummarised in Table 2. TABLE 2 Characteristics of CZ5 catalysts CZ5 CZ5CZ5 CZ5 CZ5 CZ5 CZ5 CZ5 Catalyst CZ5 P B Si BSi PB PSi PBSi PBSiF MoO₃(wt %) 15.2 14.6 14.8 14.9 14.5 14.3 14.3 14.0 13.7 NiO (wt %) 2.8 2.72.7 2.7 2.7 2.7 2.6 2.6 2.5 P₂O₅ (wt %) 0 4.6 0 0 0 4.5 4.5 4.4 4.35B₂O₃ (wt %) 0 0 2.3 0 2.3 2.1 0 2.1 2.1 SiO₂ (wt %) 0 0 0 2.1 2.2 0 2.452.3 2.3 F (wt %) 0 0 0 0 0 0 0 0 1.1 Al₂O₃ (wt %) 74.9 71.4 73.2 73.471.5 69.8 69.6 68.1 67.5 Y (wt %) 7.1 6.7 6.9 6.9 6.7 6.6 6.6 6.4 6.4

[0074] Catalyst CZ5P was then impregnated with an aqueous solutioncomprising manganese nitrate. After ageing at room temperature in anatmosphere saturated with water, the impregnated extrudates were driedovernight at 120° C. then calcined at 550° C. for 2 hours in dry air.Catalyst CZ5PMn was obtained. This catalyst was then impregnated with anaqueous solution comprising ammonium biborate and Rhodorsil EP1(Rhone-Poulenc) silicone emulsion. The impregnated extrudates were thendried overnight at 120° C. and calcined at 50° C. for 2 hours in dry airto obtain catalyst CZ5PMnBSi. Fluorine was then added to this catalystby impregnating with a dilute hydrofluoric acid solution so as todeposit about 1% by weight of fluorine. After drying overnight at 120°C. and calcining at 550° C. for 2 hours in dry air, catalyst CZ5PMnBSiFwas obtained. The characteristics of catalysts CZ5 are summarised inTable 3. TABLE 3 Characteristics of CZ5 catalysts containing manganeseCZ5 CZ5 CZ5 Catalyst PMn PMnBSi PMnBSiF MoO₃ (wt %) 14.4 13.8 13.6 NiO(wt %) 2.7 2.5 2.5 MnO₂ (wt %) 1.2 1.2 1.15 P₂O₅ (wt %) 4.4 4.2 4.1 B₂O₃(wt %) 0 2.05 2.0 SiO₂ (wt %) 0 2.3 2.3 F (wt %) 0 0 0.85 Al₂O₃ (wt %)70.7 67.6 67.0 Y (wt %) 6.6 6.4 6.3

EXAMPLE 5 Preparation of a support containing non dealuminated Y zeoliteand a silica-alumina

[0075] We produced a silica-alumina powder by co-precipitating of acomposition of 4% SiO₂, 96% Al₂O₃. A support for a hydrocrackingcatalyst containing this silica-alumina and a non globally dealuminatedY zeolite was then produced. To this end, 19.5% by weight of a nondealuminated Y zeolite with a lattice parameter of 2.453 nm, a globalSiO₂/Al₂O₃ ratio of 6.6 and a framework SiO₂/Al₂O₃ ratio of 8.6 wasused, which was mixed with 80.5% by weight of a matrix composed of thesilica-alumina prepared as above. This powder mixture was then mixedwith an aqueous solution containing 66% nitric acid (7% by weight ofacid per gram of dry gel) then mixed for 15 minutes. After mixing, thepaste obtained was passed through a die with cylindrical orifices with adiameter of 1.4 mm. The extrudates were dried overnight at 120° C. thencalcined at 550° C. for 2 hours in moist air containing 7.5% by volumeof water. Cylindrical extrudates 1.2 mm in diameter were obtained with aspecific surface area of 365 m²/g, a pore volume of 0.53 cm³/g and aunimodal pore size distribution centred on 11 nm. An X ray diffractionanalysis of the matrix revealed that it was composed of lowcrystallinity cubic gamma alumina and Y zeolite with a lattice parameterof 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.8 with a frameworkSiO₂/Al₂O₃ ratio of 14.7.

EXAMPLE 6 Preparation of catalysts containing a non dealuminated Yzeolite and a silica-alumina

[0076] Extrudates of the support containing a non dealuminated Y zeolitewith a lattice parameter of 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.8and a framework SiO₂/Al₂O₃ ratio of 14.7 prepared in Example 5 were dryimpregnated with an aqueous solution of a mixture of ammoniumheptamolybdate and nickel nitrate, dried overnight at 120° C. in air andfinally calcined at 550° C. in air. The oxide weight contents ofcatalyst CZ17 obtained are shown in Table 1. The final CZ17 catalystcontained 16.3% by weight of Y zeolite. X ray diffraction analysis ofthe matrix revealed that it was composed of low crystallinity cubicgamma alumina and Y zeolite with a lattice parameter of 2.444 nm, aglobal SiO₂/Al₂O₃ ratio of 6.6 and a framework SiO₂/Al₂O₃ ratio of 14.2.

[0077] Catalyst CZ17 was then impregnated with an aqueous solutioncomprising ammonium biborate. After ageing at room temperature in anatmosphere saturated with water, the impregnated extrudates were driedovernight at 120° C. then calcined at 550° C. for 2 hours in dry air.Catalyst CZ17B was obtained

[0078] Extrudates of the support containing the Y zeolite of Example 1were also dry impregnated with an aqueous solution of a mixture ofammonium heptamolybdate, nickel nitrate and orthophosphoric acid, driedovernight at 120° C. in air and finally calcined at 550° C. in air. Theoxide weight contents of catalyst CZ17P obtained are shown in Table 4.The final CZ17P catalyst contained 15.4% by weight of Y zeolite. X raydiffraction analysis of the matrix revealed that it was composed of lowcrystallinity cubic gamma alumina and Y zeolite with a lattice parameterof 2.444 nm, a global SiO₂/Al₂O₃ ratio of 6.7 and a framework SiO₂/Al₂O₃ratio of 14.7.

[0079] Catalyst CZ17P was then impregnated with an aqueous solutioncomprising ammonium biborate. After ageing at room temperature in anatmosphere saturated with water, the impregnated extrudates were driedovernight at 120° C. then calcined at 550° C. for 2 hours in dry air.Catalyst CZ17BP was obtained.

[0080] The characteristics of catalysts CZ17 are summarised in Table 4.TABLE 4 Characteristics of CZ17 catalysts CZ17 CZ17 CZ17 Catalyst CZ17 PB PB MoO₃ (wt %) 13.4 12.7 13.1 12.5 NiO (wt %) 2.9 2.8 2.9 2.7 P₂O₅ (wt%) 0 5.3 0 5.2 B₂O₃ (wt %) 0 0 2.15 2.2 SiO₂ (wt %) 2.68 2.53 2.6 2.5Al₂O₃ (wt %) 64.7 61.2 63.8 59.8 Y (wt %) 16.3 15.4 15.9 15.1

EXAMPLE 7 Comparison of catalysts for low pressure hydrocracking of avacuum gas oil

[0081] The catalysts prepared in the above Examples were employed undermoderate pressure hydrocracking conditions using a petroleum feed withthe following principal characteristics: Initial point 365° C. 10% point430° C. 50% point 472° C. 90% point 504° C. End point 539° C. Pour point+39° C. Density (20/4) 0.921 Sulphur (weight %) 2.46 Nitrogen (ppm byweight) 1130

[0082] The catalytic test unit comprised two fixed bed reactors inupflow mode. 40 ml of catalyst was introduced into each of the reactors.The catalyst for the first hydrotreatment step of the process, HTH548from Procatalyse, comprising a group VIB element and a group VIIIelement deposited on alumina, was introduced into the first reactor,through which the feed passed first. A hydrocracking catalyst (CZ5series) was introduced into the second reactor, through which the feedpassed last. The two catalysts underwent in-situ sulphurisation beforethe reaction. It should be noted that any in-situ or ex-situsulphurisation method is suitable. Once sulphurisation had been carriedout, the feed described above could be transformed. The total pressurewas 8.5 MPa, the hydrogen flow rate was 500 liters of gaseous hydrogenper liter of injected feed, and the hourly space velocity was 0.8 h⁻¹.The two reactors operated at the same temperature.

[0083] The catalytic performances are expressed as the gross conversionat 400° C. (GC), the gross selectivity for middle distillates (150-380°C. cut) (GS) and the hydrodesulphuration (HDS) and hydrodenitrogenation(HDN) conversions. These catalytic performances were measured for thecatalyst after a stabilisation period, generally of at least 48 hours,had passed.

[0084] The gross conversion GC is taken to be:

[0085] GC=weight % of 380° C.^(minus) of effluent.

[0086] The gross selectivity GS for middle distillates is taken to be:

[0087] GS=100* weight of (150° C.-380° C.) fraction/weight of 380°C.^(minus) fraction of effluent.

[0088] The hydrodesulphuration conversion HDS is taken to be:

[0089] HDS=(S_(initial)−S_(effluent))/S_(initial)*100=(24600−S_(efflueent))/24600*100

[0090] The hydrodenitrogenation conversion HDN is taken to be:

[0091]HDN=(N_(initial)−N_(effluent))/N_(initial)*100=(1130−N_(effluent))/1130*100

[0092] Table 5 shows the gross conversion GC at 400° C., the grossselectivity GS, the hydrodesulphuration conversion HDS and thehydrodenitrogenation conversion HDN for the test catalysts. TABLE 5Catalytic activities for catalysts for partial hydrocracking at 400° C.GC GS HDS HDN (wt %) (wt %) (%) (%) CZ3 NiMo/Y 50.9 79.8 98.9 97.1 CZ3PNiMoP/Y 52.2 79.0 99.4 98.4 CZ3B NiMoB/Y 53.3 79.1 99.4 98.4 CZ3SiNiMoSi/Y 54.3 79.3 99.4 98.6 CZ3BSi NiMoBSi/Y 54.9 79.5 99.5 98.8 CZ3PBNiMoPB/Y 53.5 79.0 99.3 98.5 CZ3PSi NiMoPSi/Y 53.9 79.0  99.25 98.5CZ3PBSi NiMoPBSi/Y 54.8 78.9 99.4 98.9

[0093] The results of Table 5 show that the performances-of catalyst CZ3were greatly improved when B and/or silicon was/were added. Theimprovement in the gross conversion in particular should be noted, whilethe selectivity for middle distillates remained constant. Further, thepresence of boron and/or silicon tended to substantially improve the HDSand HDN. TABLE 6 Catalytic activities for catalysts CZ3 and CZ17 withequivalent compositions for partial hydrocracking at 400° C. GC GS HDSHDN (wt %) (wt %) (%) (%) CZ17 NiMo/Y—SiAl 53.3 78.9 97.8 97.1 CZ3SiNiMoSi/Y 54.3 79.3 99.4 98.6 CZ17P NiMoP/Y—SiAl 53.2 79.1  98.25 97.5CZ3PSi NiMoPSi/Y 53.9 79.0  99.25 98.5 CZ17B NiMoB/Y—SiAl 53.7 79.1 98.397.1 CZ3BSi NiMoBSi/Y 54.9 79.5 99.5 98.8 CZ17PB NiMoPB/Y—SiAl 53.8 78.798.1 97.7 CZ3PBSi NiMoPBSi/Y 54.8 78.9 99.4 98.9

[0094] The results of Table 6 show that it is advantageous to introducesilicon into the already prepared catalyst rather than in the form of asupport containing silicon obtained from a silica-alumina. This is truewhether or not the catalyst contains phosphorous. It is thusparticularly advantageous to introduce silicon to a precursor alreadycontaining group VIB and/or VIII elements and optionally at least one ofelements P, B and F.

[0095] Catalysts containing an alumina acidified by boron and/or siliconand a globally non dealuminated zeolite are thus of particularimportance for partial hydrocracking of a vacuum distillate type feedcontaining nitrogen at a moderate hydrogen pressure.

EXAMPLE 8 Comparison of catalysts for higher pressure hydrocracking of avacuum gas oil

[0096] The catalysts prepared in Examples 3 and 4 were employed underhigh pressure (12 MPa) hydrocracking conditions using a petroleum feedwith the following principal characteristics: Initial point 277° C. 10%point 381° C. 50% point 482° C. 90% point 531° C. End point 545° C. Pourpoint +39° C. Density (20/4) 0.919 Sulphur (weight %) 2.46 Nitrogen (ppmby weight) 930

[0097] The catalytic test unit comprised two fixed bed reactors inupflow mode. 40 ml of catalyst was introduced into each of the reactors.Catalyst 1 for the first hydrotreatment step of the process, HR360 fromProcatalyse, comprising a group VIB element and a group VIII elementdeposited on alumina, was introduced into the first reactor, throughwhich the feed passed first. The catalyst for the second step, i.e., thehydroconversion catalyst (CZ5 series), was introduced into the secondreactor, through which the feed passed last. The two catalysts underwentin-situ sulphurisation before the reaction. It should be noted that anyin-situ or ex-situ sulphurisation method is suitable. Oncesulphurisation had been carried out, the feed described above could betransformed. The total pressure was 12 MPa, the hydrogen flow rate was1000 liters of gaseous hydrogen per liter of injected feed, and thehourly space velocity was 0.9 h⁻¹.

[0098] The catalytic performances are expressed as the temperature atwhich a gross conversion of 70% is produced and by the grossselectivity. These catalytic performances were measured for the catalystafter a stabilisation period, generally of at least 48 hours, hadpassed.

[0099] The gross conversion GC is taken to be:

[0100] GC=% by weight of 380° C.^(minus) of effluent.

[0101] The gross selectivity GS for middle distillates is taken to be:

[0102] GS=100* weight of (150° C.-380° C.) fraction/weight of 380°C.^(minus) fraction of effluent.

[0103] The reaction temperature was fixed so as to obtain a grossconversion GC of 70% by weight. Table 7 shows the reaction temperatureand gross selectivity for catalysts from the CZ5 series. TABLE 7Catalytic activities for CZ5 catalysts for hydrocracking T (° C.) GS (%)CZ5 NiMo/Y 396 71   CZ5P NiMoP/Y 395 71.4 CZ5B NiMoB/Y 395 71.5 CZ5SiNiMoSi/Y 395 71.5 CZ5BSi NiMoBSi/Y 394 71.8 CZ5PB NiMoPB/Y 395 71.2CZ5PSi NiMoPSi/Y 394 71.5 CZ5PBSi NiMoPBSi/Y 393 71.4 CZ5PBSiFNiMoPBSiF/Y 391 70.9 CZ5PMn NiMoPMn/Y 394 71.2 CZ5PMnBSi NiMoPMnBSi/Y393 71.3 CZ5PMnBSiF NiMoPMnBSiF/Y 390 71.2

[0104] Adding boron and/or silicon to the catalyst containing globallynon dealuminated zeolite retained the very high selectivity of catalystCZ5 with a lower reaction temperature since a gain of 3° C. in thetemperature was observed with respect to catalyst CZ5PBSi. Further, ifmanganese and/or fluorine was added, an improvement in the convertingactivity was also observed with no degradation of the gross selectivityfor middle distillates.

1. A catalyst comprising: 0.1-99.7% by weight of at least one aluminamatrix; 0.1-80% by weight of at least one globally non dealuminated Yzeolite with a lattice parameter of more than 2.438 nm, a globalSiO₂/Al₂O₃ mole ratio of less than 8, and a framework SiO₂/Al₂O₃ moleratio of less than 21 and more than the global SiO₂/Al₂O₃ mole ratio;0.1-30% by weight of at least one group VIII metal and/or 1-40% byweight of at least one group VIB metal (% oxide); 0.1-20% by weight ofat least one promoter element selected from the group formed by boronand silicon (% oxide); 0-20% by weight of at least one group VIIAelement; 0-20% by weight of phosphorous (% oxide); 0.1-20% by weight ofat least one group VIIB element.
 2. A catalyst according to claim 1, inwhich the group VIIA element is fluorine.
 3. A catalyst according to anyone of the preceding claims, in which the group VIIB element ismanganese.
 4. A hydrocracking process using a catalyst according to anyone of the preceding claims, carried out at a pressure of at least 2MPa, a temperature of at least 230° C., using a quantity of hydrogen ofat least 100 Nl hydrogen/l of feed and with an hourly space velocity of0.1-10 h⁻¹.
 5. A process according to claim 4, in which the pressure is2-12 MPa, the temperature is 300-480° C. and the conversion is less than55%.
 6. A process according to claim 5, in which the pressure is 7.5-11MPa.
 7. A process according to claim 4, in which the pressure is atleast 8.5 MPa, the temperature is 300-430° C. and the conversion is atleast 55%.
 8. A process according to claim 5, in which the feed ishydrotreated prior to hydrocracking.
 9. A process according to claim 8,in which the hydrotreatment catalyst contains at least one group VIIImetal, at least one group VIB metal, phosphorous and optionally boron.10. A process according to claim 5, in which the pressure is 8-11 MPa.